Older age is associated with a decline in glucose tolerance which itself is an important precursor to the development of non-insulin-dependent mellitus (NIDDM) and subsequent cardiovascular disease (CVD). We propose that the decline in glucose tolerance with aging can be accounted for, to a significant extent, by the concomitant decline in physical activity. Thus, the overall purpose of the proposed study is to determine the impact of aerobic exercise on improvements in glucose regulation in older people. To date we have established the reliability of the clamp procedure on 3 younger subjects and 2 older subjects. In addition we have tested the acute effects of a single bout of exercise (75-80% max) on 12 hour or 24 hour glucose disposal in 8 subjects.